ABSTRACT This study employs first‐principles calculations to explore the structural, electronic, and optical coating properties of Ag‐based ternary and quaternary chalcogenide compounds. Elastic constants satisfy all Born stability criteria, and the Pugh ratio B/G , with values exceeding 2, classifies all studied compounds as inherently stable and ductile materials. The findings indicate that all compounds investigated are direct bandgap semiconductors, with bandgap values of 0.963 eV for AgGaTe 2 , 0.736 eV for AgInTe 2 , 0.49 eV for Ag 2 CdSnTe 4 , and 0.868 eV for Ag 2 InGaTe 4 . Analysis of optical properties shows that all thin‐films demonstrate high absorbance (∼75%) in the visible spectrum for film thicknesses greater than 1600 nm. Additionally, the computed absorption coefficients, approximately 10 4 cm −1 , affirm the strong light‐harvesting capability of these materials, making them promising candidates for solar cell absorber layers. The spectroscopic limited maximum efficiency (SLME) was assessed, revealing a significant increase for wavelengths beyond 500 nm, with maximum theoretical efficiencies of 29.22% for AgGaTe 2 , 24.30% for AgInTe 2 , and 27.91% for Ag 2 InGaTe 4 , all aligning with optimal bandgap values between 0.73 and 1.0 eV. These results indicate that the newly investigated quaternary compound Ag 2 InGaTe 4 displays exceptional optoelectronic properties, indicating its potential as a strong candidate for thin‐film solar cell applications.

The full potential linearized augmented plane wave (FP-LAPW) technique was performed to give valuable insights into the elasto-mechanical, electronic structure, and magneto-optical characteristics of the cubic double perovskite oxide Sr2AlMoO6. The prediction of structural properties demonstrates the compound's enduring ferromagnetic stability. The generalized gradient approximation (GGA) and the GGA+U approach were performed to calculate the spin-polarized electronic band structure and density of states, which revealed that the compound exhibits a half-metallic characteristic, whereas most spin channels exhibit metallic behavior. In contrast, a minority of spin channels display semiconducting properties. The calculated significant values of the bulk and Young modulus also categorize the material as robust and more rigid The computed values for B/G and Cauchy pressure (C12-C44) collectively indicate the compound's ductile characteristics. The calculations of different optical spectra affirm that this compound is highly suitable for various device applications across a wide range of the electromagnetic spectrum.

This study investigates the orthorhombic chalcogenide perovskite LaScSe3 using density functional theory (DFT) and the full-potential linearized augmented plane wave (FP-LAPW) method implemented in the Wien2K package. Structural properties were analyzed using the WC-GGA approximation, confirming its stability in a non-magnetic state. The electronic structure was examined under mBJ-GGA, mBJ-GGA + SOC, and mBJ-GGA + U + SOC approximations, yielding direct band gaps of 1.62 eV, 1.52 eV, and 1.80 eV, respectively, with the conduction band minimum and valence band maximum at the Gamma-point. Elastic constants confirm mechanical stability, ductility, and elastic anisotropy. Optical properties highlight significant absorption in the ultraviolet range, driven by La-f and Se-p states, indicating its suitability for optoelectronic applications. Thermoelectric calculations demonstrate high Seebeck coefficients, low thermal conductivity, and excellent power factors, emphasizing LaScSe3 ' s potential for thermoelectric devices. These findings establish LaScSe3 as a promising candidate for advanced optoelectronic and thermoelectric applications.

Lead-free double halide perovskites like Rb2Ag(Ga/In)Br-6 have demonstrated themselves potential candidates in solar cell research owing to their environmental friendliness, stability, and exceptional performance. This study comprehensively analyzes the structural, mechanical, optoelectronic and optical coating features, as well as thermodynamic and thermoelectric properties of two Rb2AgGaBr6 and Rb2AgInBr6 compounds. Using the Wien2k code with GGA + mBJ exchange-correlation potentials, we confirm their structural stability in cubic phase Fm-3m and identifying them as direct band gap semiconductors (Gamma -> Gamma) of 0.38 eV and 1.0644 eV, respectively. Then, optical analysis reveals broad absorption bands across visible and ultraviolet wavelengths, making them suitable for photovoltaic absorbers. Finally, the thermoelectric investigations under varying temperatures show favourable properties, such as a high Seebeck coefficient with poor electronic thermal conductivity. This also yields exceptional value (0.96 and 0.994 for Rb2AgGaBr6, Rb2AgInBr6, respectively) of figure of merit (ZT) at room temperature and chemical potential mu-mu 0 = - 0.09eV near the Fermi energy level, enhancing their potential for thermoelectric applications. These findings underscore the versatility and promising future of Rb2Ag(Ga/In)Br-6 as important semiconductors processing for optoelectronic, thermoelectric, and mechanical devices.

In this study, we systematically examined the physical properties of CsSnX3 (X = Cl, Br) by employing the (FPLAPW) method within the (GGA) and GGA + mBJ approximations. The investigated compounds exhibit direct bandgap semiconducting with an ionic-covalent mixture in CsSnX3 bonds. Notably, CsSnCl3 and CsSnBr3 exhibit exceptional light absorption and optical conductivity, making them appropriate for a particular application. Elastic constants of compounds and different moduli are determined for the first time. Considering the thermodynamic model, perovskite materials consistently display thermodynamic properties such as heat capacity, Debye temperature, Gr & uuml;neisen constant for a range of pressures and temperatures. The calculations of transport properties by using BoltzTrap code reveals a high figure of merit close to unity for CsSnX3 (Cl, Br) at room temperature, highlighting their potential for thermoelectric applications. Overall, CsSnX3 (Cl, Br) perovskite exhibit remarkable physical properties and environmental compatibility, positioning them as up-and-coming candidates for optoelectronic and thermoelectric applications.

In this study, we systematically examined the physical properties of CsSnX3 (X = Cl, Br) by employing the (FP-LAPW) method within the (GGA) and GGA + mBJ approximations. The investigated compounds exhibit direct bandgap semiconducting with an ionic-covalent mixture in CsSnX3 bonds. Notably, CsSnCl3 and CsSnBr3 exhibit exceptional light absorption and optical conductivity, making them appropriate for a particular application. Elastic constants of compounds and different moduli are determined for the first time. Considering the thermodynamic model, perovskite materials consistently display thermodynamic properties such as heat capacity, Debye temperature, Grüneisen constant for a range of pressures and temperatures. The calculations of transport properties by using BoltzTrap code reveals a high figure of merit close to unity for CsSnX3 (Cl, Br) at room temperature, highlighting their potential for thermoelectric applications. Overall, CsSnX3 (Cl, Br) perovskite exhibit remarkable physical properties and environmental compatibility, positioning them as up-and-coming candidates for optoelectronic and thermoelectric applications.

In this study, an investigation of the structural stability, elastic, optoelectronic, thermoelectric, optical thin-film coating, and thermodynamic properties of K2Ag(Ga/In)Br6 (lead-free halide double perovskites, HDPs) was performed using first-principles calculations. The optimized structural parameters are in good agreement with the available data. Furthermore, Goldsmith's tolerance factor indicates an ideal value for both double perovskites, ensuring the structural stability of the cubic perovskites, and the elasticity parameters were analyzed to ensure the mechanical stability of the cubic phase. Direct and reduced band gaps of 0.4524 eV and 1.064 eV with semiconductor behavior are found for K2AgGaBr6 and K2AgInBr6, respectively, through adoption of the modified Becke-Johnson potential scheme. The absorption coefficient, refractive index, and dielectric function, as some of the optical properties, in addition to the optical thin-film properties, are well discussed, and the values suggest that these materials are promising candidates for different devices, such as optoelectronic and photovoltaic energy devices. In terms of the thermodynamics, the HDPs display favorable characteristics across various temperature and pressure ranges. Additionally, we assessed the thermoelectric properties, considering the power factor, Seebeck coefficient, thermal and electronic conductivities, and figure of merit. The current predictions suggest that these lead-free halide double perovskites have strong potential for application in thermoelectricity and photovoltaics.

This study examines the physical characteristics of Co2Te3O8 in the spiroffite structure using an ab initio approach. The optimization of the Co2Te3O8 structure, in both nonmagnetic and magnetic states, indicates that the magnetic state is more stable than the non-magnetic one. Thermodynamic properties under various temperatures and pressures, calculated via the quasi-harmonic approximation, reveal that the specific heat capacity of spiroffite Co2Te3O8 conforms to the Debye model and satisfies the Dulong and Petit limits. The electrical, magnetic, and optical properties of Co2Te3O8 are investigated using the GGA and TB-mBJ approximations. Analysis of the density of states and the band structure indicates that spiroffite Co2Te3O8 exhibits semiconductor characteristics in both the spin up and spin down channels. The study is extended to apply hydrostatic pressure to assess the electronic and magnetic properties of both unstrained and strained structures of Co2Te3O8. It is found that within the investigated pressure range (0–15 GPa), no structural changes are observed. Furthermore, a slight decrease in the spin up gap is noted, while no appreciable changes are observed in the spin down gap. Moreover, the investigation into the spin-polarized thermoelectric properties of the material reveals that it achieves a high figure of merit, approximately 0.99, across broad temperature spectra. This performance highlights its suitability as a candidate for thermoelectric power generation. Finally, optical properties calculations on spiroffite Co2Te3O8 reveal efficient absorption in the ultraviolet region.

Technological development cannot take place without a deep knowledge of materials and their physical properties. Complex oxides constitute a family of materials characterized by specific characteristics prompting them for potential technological applications. The results of a theoretical study related to the structural, thermodynamic, electronic, optical, and magnetic properties of the Dy 2 Be 2 GeO 7 complex oxide are presented. The current study is accomplished using the “Full Potential (FP) Linearized (L) Augmented Plane Wave Plus Local Orbitals (APW + lo)” formalism as incorporated in the WIEN2k computational code in the “density functional theory” framework. To approximate the exchange and correlation effects, the PBE-GGA formalism of the “generalized gradient approximation” is used. Furthermore, “Tran-Blaha modified Becke–Johnson potential” is used to better describe the electronic structure. The equilibrium structural parameters are in good agreement with the corresponding measured data reported in the literature. The thermodynamic properties of the title compounds are explored via the quasi-harmonic approximation over temperature and pressure ranges from 0 to 700 K and 0 to 10 GPa, respectively. The electronic properties are determined with spin-polarized inclusions. Finally, the optical properties are examined with a detailed discussion of different optical parameters, including dielectric function, absorption coefficient, optical conductivity, reflectivity, and refractive index spectra. The Dy 2 Be 2 GeO 7 complex oxide with a non-centrosymmetric tetragonal structure shows a negative birefringent, therefore it is a possible candidate for applying to the birefringent field and nonlinear optical process. To our best knowledge, the current study is the first effort to explore the physical characteristics of the considered complex oxide.

The present work is a theoretical study of the structural and spin-polarized dependent optoelectronic thermoelectric properties of the melilite-typeGd2Be2GeO7 compound, using the full potential linearized augmented plane wave approach in the framework of density functional theory. The predicted structural parameters are in good accordance with the measured counterparts. It is found that the title compound is more stable in the ferromagnetic order than in the non-magnetic order. The calculated band structure using the modified Becke–Johnson potential reveals that the studied compound has a wide bandgap of 3.78 eV. The frequency-dependent linear optical spectra are studied in an energy range expanding from 0 to 30 eV. Finally, the semi classical Boltzmann theory as incorporated in the Boltztrap code is used to study the spin-polarized dependent transport properties. The obtained results show that Gd2Be2GeO7 is a potential candidate for conversion energy device applications.

In this paper, we present the results of a detailed computational study of the structural, electronics, optical, thermodynamic, and thermoelectric properties of the AgXO2 (X = In, Y) materials with delafossite-type structure, by using the "full-potential linearized augmented plane wave (FP-LAPW)" method. The calculated structural parameters of the title compounds are in excellent agreement with the available theoretical data. We have explored the dynamical stability of the AgXO2 compounds by investigating the phonon dispersion curves. The optoelectronic characteristics of the studied compounds were accurately described at the level of the "Trans Blaha modified Becke-Johnson (TB-mBJ)" approach to model the exchange-correlation potential. On the other hand, the optical characteristics of the AgInO2 and AgYO2 thin films were investigated in the wavelength range 200-750 nm for three different thicknesses: 300, 600 and 1300 nm on a transparent substrate (glass: n(glass) = 1.5, k(glass) = 0). Thermodynamic and thermoelectric properties of the considered compounds were predicted by employing the "quasi-harmonic Debye model" and the Boltzmann transport theory.

To find a seemly solution to the problems of efficiency dependency of the hybrid PV/TE devices, on important factors like "high-absorbance with high-ZT materials" and improving the performance of existing devices, are essential research topics nowadays. In this regard, we report here optical coating, and thermoelectric features of the kesterite-structured Ag2CdSnS4 and Ag2CdSnSe4 compounds. These investigations are performed at the level of "full-potential linearized augmented plane wave plus local orbital method, FP-L(APW + lo)" framed within the "density functional theory (DFT)" method comprised with relativistic effects. Our study of the optical coating shows that both the investigated materials have a good level of absorbance (A), approximately 80% in the visible part of the spectra. Further, we found that the magnitude of reflectance (R) of the Ag2CdSnX4 (X = S, Se) thin films increase with increasing film thickness, while the response of the transmittance (T) spectra is reverse to it. These results are corroborated by the study of the transport properties by employing the Boltztrap code, and correspondingly electrical conductivity, Seebeck coefficient, electronic thermal conductivity as well as the figure of merit parameters were evaluated and analyzed as a function of the chemical potential for both investigated compounds at five values of the temperatures. Hence our obtained results show that both the investigated semiconductor materials exhibit strong potential for the application of hybrid PV/TE systems.

First principles calculations were carried out on the SrMoO4 compound which has been of interest owing to its technologically important physical properties. The structural, electronic, optical and thermal properties of this compound have been investigated under low pressure (LP) through the full potential linearized augmented plane wave method (FP-LAPW) within the framework of density functional theory. It is found that the phase transition from zircon to scheelite type structure occurs at negative pressure. The calculated ground state properties in scheelite structure are found to be in good accord with previously published data. Using the recently developed Tran Blaha-modified Becke Johnson approach, we have also studied the electronic band structure of this compound which shows the semiconducting behavior with a direct band gap of 4.30 eV in the scheelite phase, whereas the band gap is found to be 2.18 eV in the zircon phase. Various thermodynamic properties including the thermal volume expansion coefficient and heat capacities at constant volumes and pressures were calculated via the quasi-harmonic Debye model at different temperatures (0–1000 K). Furthermore, optical properties such as complex dielectric function, refractive index, and reflectivity spectra of the titled compound were studied for incident electromagnetic waves in an energy range up to 16 eV. The contributions to various transitions peaks in the optical spectra are analyzed and discussed with the help from the energy dependent imaginary part of the dielectric function.

The present work aims at investigating the electronic, optical, photovoltaic and thermoelectric properties of AgBiS2 compound using the density functional theory (DFT) and the modified Becke-Johnson exchange-correlation potential (mBJ). Both hexagonal Matildite and cubic Schapbachite polymorphs were considered. The hexagonal phase is found to be indirect gap semiconductor with band gap energy of about 1.07 eV and high absorption coefficient of 10(6) cm(-1), whereas the cubic phase were metallic. The analysis of band alignment of Matildite with some binary oxides and sulfides revealed interesting results. The photovoltaic properties of AgBiS2 confirmed that Matildite phase could achieve a short-circuit current of 22 mA/cm(2) and conversion efficiency of 20%. Also, we demonstrated that including photon recycling with a proper solar cell design could improve the conversion efficiency. Moreover, interesting thermoelectric performance has been confirmed.

In this study, first-principles investigations were performed using the full-potential linearized augmented plane-wave method of the structural and optoelectronic properties of thorium germinate (ThGeO4), a high-K dielectric material. Under ambient conditions, the structural properties calculated for ThGeO4 in the zircon phase were in excellent agreement with the available experimental data. Furthermore, using the modified Becke-Johnson correction method, the calculated band gaps and optical constants accurately described this compound. Finally, the thermal properties were predicted over a temperature range of 0700 K and pressures up to 11 GPa using the quasi-harmonic Debye model, where the variations in the heat capacity, primitive cell volume, and thermal expansion coefficients were determined successfully.

The optical absorbance of four ternary thin films, i.e. MgSiP2, MgGeP2, MgSiAs2, MgGeAs2 have been theoretically examined over a wide range of wavelength from 300 nm to 800 nm. The combination of first-principle electronic structure calculations and the optical matrix approach for modeling the multi layer assembly have been employed for theoretical studies. The analysis of the calculated absorbance spectra at room temperature with unpolarized light and normal incidence, revealed that MgGeAs2 with a direct energy band gap of 1.6 eV exhibit a considerable high optical absorption, where a thickness of 3.2 mu m of this thin film is sufficient to absorb 90% of the incident light and generates a maximum photocurrent of similar to 23 mA/cm(2). (C) 2016 Elsevier B.V. All rights reserved.

In the present study, the structural, thermal, and electronic properties of some important orthosilicate dielectrics, such as the ZrSiO4, ZrGeO4, and HfSiO4 compounds, have been investigated theoretically with the use of first-principle calculations. We attribute the application of the modified Becke–Johnson exchange potential, which is basically an improvement over the local density approximation and the Perdew–Burke–Ernzerhof exchange–correlation functional, for a better description of the band gaps of the compounds. This resulted in a good agreement with our estimated values in comparison with the reported experimental data, specifically for the ZrSiO4, and HfSiO4 compounds. Conversely, for the ZrGeO4 compound, the calculated electronic band structure shows a direct band gap at the Γ point with the value of 5.79 eV. Furthermore, our evaluated thermal properties that are calculated by using the quasi-harmonic Debye model indicated that the volume variation with temperature is higher in the ZrGeO4 compound as compared to both the ZrSiO4 and HfSiO4 compounds, which is ascribed to the difference between the electron shells of the Si and Ge atoms. Therefore, these results also indicate that while the entropy (S) and enthalpy (U) parameters increase monotonically, the free energy (G), in contrast, decreases monotonically with increasing temperature, respectively. Moreover, the pressure and temperature dependencies of the Debye temperature Θ, thermal expansion coefficient, and heat capacities C V were also predicted in our study.

The results of a first-principle study of the structural, electronic, and thermal properties of a \(\hbox {BaS}_{1-{x}}\hbox {Te}_{{x}}\) alloy, using the full-potential linear muffin-tin-orbital (FP-LMTO) method in the framework of density functional theory, within both the local density approximation and the generalized gradient approximation are presented. The composition effect on lattice constants, bulk moduli, band gaps, and effective masses is analyzed. The quasi-harmonic Debye model, using a set of total energy versus volume calculations obtained with the FP-LMTO method, is applied to study the thermal and vibrational effects. The temperature effect on the lattice parameters, thermal expansions, heat capacities, and Debye temperatures is determined from the non-equilibrium Gibbs functions. The microscopic origins of the bowing parameter were explained using the approach of Zunger and coworkers.

The electronic structure, mechanical and thermodynamic properties of Fe2VX, (with X = Al and Ga), have been studied self consistently by employing state-of-the-art full-potential linearized approach of augmented plane wave plus local orbitals (FP-LAPW + lo) method. The exchange-correlation potential is treated with the local density and generalized gradient approximations (LDA and GGA). Our predicted ground state properties such as lattice constants, bulk modulus and elastic constants appear more accurate when we employed the GGA rather than the LDA, and these results are in very good agreement with the available experimental and theoretical data. Further, thermodynamic properties of Fe2VAl and Fe2VGa are predicted with pressure and temperature in the ranges of 0–40 GPa and 0–1500 K using the quasi-harmonic Debye model. We have obtained successfully the variations of the heat capacities, primitive cell volume and volume expansion coefficient.